Operation of a passively mode-locked extended-cavity surface-emitting diode laser in multi-GHz regime

We report on passive mode-locking of vertical cavity surface-emitting diode lasers at 980-nm wavelength, applied to different extended resonator configurations. Stable mode-locking producing pulses of approximately 50 ps in duration at up to 6-GHz repetition rate has been achieved. The use of external feedback results in pronounced harmonic pulse generation, extending the operational range of these new devices.